The study was aimed at evaluating the hypoglycaemic effects of melatonin and Azadirachta indica administration on blood glucose levels in streptozotocin (STZ) induced diabetic Wistar rats. To achieve this, thirty Wistar rats were used in the study. The animals were assigned into the following groups: Group 1: Normal control + normal saline orally Group 2: Diabetic control + normal saline orally; Group 3: Diabetic + A. Indica (200 mg/kg b w) orally; Group 4: Diabetic + melatonin (10 mg/kg b w) IP; Group 5: Diabetic + A. Indica (200 mg/kg b w) orally + melatonin (10 mg/kg b w) IP; Group 6: Diabetic + metformin (500 mg/kg b w) orally. The extract and drug were administered once daily for a period of three (3) weeks respectively. The fasting Blood glucose level was taken at an interval of 7 days. The results showed that there was significant reduction (p ≤ 0.05) in blood glucose levels in Azadirachta indica leaves extract treated diabetic group (DAI), melatonin treated diabetic group (DML) and the extract and melatonin combined treated diabetic group (DAI+DML) as compared with the metformin treated diabetic group and Diabetic control group. The results showed that melatonin and Azadiachta indic ethanol leaves extract possesses hypoglycaemic properties and synergistically reduced blood glucose levels in streptozotocininduced diabetic Whistar rats.